This invention relates to an electrofluidic converter of the type comprising a bistable fluidic element which is provided with a supply input, two outputs separated by a jet splitter, and two control inputs, with each output of the converter being connected to a respective control input of the fluidic element through a feedback conduit, and with the feedback conduits being adapted to be closed or cleared by an electromagnetically operated valve opening in the direction of fluid flow through the associated feedback conduit then closed thereby.
In electrofluidic converters of this type, the switching is triggered in the same manner as in a feedback fluid oscillator by a power pressure impulse propagating in the feedback conduits at sound velocity. With a corresponding dimensioning of the feedback conduits, the frequency of such fluid oscillators is about 1000 Hz; cf. Multrus, Pneumatische Logikelemente und Steuerungssystems (Pneumatic Logic Elements and Control Systems), published by Krausskopf Verlag GmbH, Mainz, 1970, page 198.
The operation of the electrofluidic converter is initiated, in accordance with the disclosure of the mentioned copending application, so that the oscillation of the fluid oscillator is interrupted by closing one feedback conduit by means of the electromagnetically actuated valve. The switching over is effected by clearing the instantaneously closed feedback conduit and closing the hitherto open one. The switching operation of the valve is considerably augmented by the pressurized fluid flowing through the feedback conduit, and, with a corresponding dimensioning of the fluid element and an appropriate supply pressure, in such a manner that the inertia of the valve affects the frequency of the electrofluidic converter to only a small extent.
The result of the support or augmenting of the switching operation by the pressurized fluid is that the magnet system need provide only the holding forces for the magnetic armature of the valve in the closed position, which forces are but very small with the narrow air gaps which are easily obtainable in such a case.
One embodiment disclosed in the mentioned copending application provides that both feedback conduits are alternately opened or closed by a single valve comprising a double-seat valve body which is designed as a magnetic armature. The bistable fluid element swtiches already upon a minimum lifting of the magnetic armature from the seat, clearing the communication between the feedback conduit and the respective control input. In consequence, a pressurized fluid impulse is produced in the other feedback conduit, acting on the magnetic armature in a manner such that the motion of the armature is checked or reversed, prior to the closure of this other feedback conduit.
In order to prevent the fluid element from switching again in this manner, the feedback conduits are provided with capacities so that the augmenting of the switching operation by the pressurized fluid acting on the magnetic armature through one feedback conduit is maintained for a longer period of time, and the transit time of the pressurized fluid impulse in the other feedback conduit is extended.